PROCESS FOR MANUFACTURING A BOAT HULL

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 60/657,645, filed March 1 , 2006.

FIELD OF THE INVENTION

The present invention relates to a process of manufacturing a boat hull, deck, or other large laminate parts. The process utilizes a closed molded system for producing a unitary laminate part, whereby a pre-core and stringers are integrally molded during a reaction injection molding process.

BACKGROUND AND SUMMARY OF THE INVENTION Large fiberglass parts, such as boat hulls and large containers use stringers and bulkheads inside the part to increase their strength. The ribs or stringers create sections or flat parts between them. These flat parts are where one of the improvements arises. In an attempt to increase the strength of the laminate a closed mold system has been utilized to optimize strength through thickness and shape.

Traditionally, a fiberglass boat hull is fabricated using a one-sided open mold where layers of laminate are applied on top of one another. The first layer is generally the outside layer made of a gel coat and subsequent fiberglass mat and resin layers are put down thereafter. In the middle of the laminate a core of wood, honeycomb, foam, etc. is applied. A final layer of fiberglass and resin is then applied to the core. Stringers, bulkheads and other structures are fabricated later.

There are many disadvantages of the traditional open mold hand lay up process. For example, it takes many labor hours to fabricate a hull using the traditional process because each layer is applied by hand. Further, because the mold is open, workers are often exposed to toxic fumes from the resin. Also, the old method creates voids in the laminate which can require post lamination repair. Moreover, the traditional method only molds one side of the part at a time, which decreases the quality of the part. Moreover, the old method is not very reproducible, which decreases consistency of the final hull thus making no two parts the same. Further, the old method results in an unfinished interior surface, such as the headliner or engine compartment, which is labor intensive to later finish. Accordingly, it is therefore desirable to overcome the aforementioned problems with a new, less

expensive, faster producing, higher quality, more repeatable process for molding a hull for a vessel.

One aspect of the present invention uses a two-sided closed mold method of manufacturing a large hull for a boat, container, etc. With closed molding, the shape of both the outside and inside of the part can be controlled. Another aspect of the invention has the shape of the flats of the laminate in a concave manner by which the square or rectangle flat sections of the inside of the part have a slight dish shape to them. An additional aspect of the invention has the stringer, bulkhead, and gusset system built collectively as a unitary structure into the hull.

One form of the present invention creates a hull having one or both sides of the laminate that are dish shaped. The dish shape will enhance the strength of the laminate without increasing the core thickness or matt and resin thickness. If only one side of the laminate is dished then it would actually decrease the amount of the core material in the laminate. If both sides of the core are dish shaped, meaning one side is concave and one side is convex, then the core would be the same thickness assuming both convex and concave shapes are consistent in size and shape. This dish shaped portion of the hull reacts against the pressure that is being applied to the bottom of the boat by the waves, thus making the laminate stronger by shape.

A second form of the present invention provides an improved boat hull design with an integrally molded stringer, bulkhead, and gusset system for creating a one piece unitary structure. The resulting boat hull is stronger, takes less time to manufacture, has improved fit and finish from the inside of the boat hull, and eliminates the need for finishing the engine compartment, a typical additional step in the traditional method of manufacturing a hull.

A third form of the present invention includes a method of manufacturing a boat hull using a two part closed molding process comprising the steps of building hull A and B molds, said molds having a top, bottom and a side, installing inserts into their respective molds, introducing the hull bottom and hull sides with material, and venting excess coring agent out of the top of the mold to allow for expansion. Next hull B mold and hull A mold are separated, sheeting hull bottom core with material, pulling stringer, bulkhead and engine compartment inserts, introducing core agent, pulling core and draping core with fiberglass mat. Pulling remaining inserts from molds, spraying molds with protective agent, inserting core into mold, closing molds, injecting material and releasing part.

A forth form of the invention includes a boat hull constructed using a closed mold processes, comprising a first layer of composite material, a core layer adjacent to the first layer, and a second layer of composite material.

The novel process has the capability of not only producing a boat hull or deck, but other large parts as well. Other examples include fuselage and plane parts for the aerospace industry, rocket housings and shells for the military and defense industry, containers for the storage, transportation and aggregate business, trailer shells for the truck and trailer business and housing units for the housing industry. Any large item which can be produced in a closed molded system needing a core for it's laminate can use this invention.

Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

Figure 1 illustrates a cross section of a boat hull of the present invention;

Figures 2a- 2c illustrate a flow diagram of the steps in the method for manufacturing the present invention; and

Figure 3 is a cross sectional view of the boat hull after it has been constructed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. For discussion purposes only, a boat hull construction will be described.

With reference to Fig. 1 , an improved boat hull mold 10 is illustrated with the configuration of the remainder of the boat 12 shown in phantom. The boat hull mold 10 utilizes a unique closed molded system that employs an exterior hull mold 14, an exterior insert 16, a core 18, an interior insert 20, and an interior hull mold 22. Stringer inserts 24, 26, and 28, may be integral or located adjacent to the core 18 and are located within the engine compartment 30 and throughout the hull 116. The exterior mold 14 sits on a base 32 during the molding process. A bulkhead 34 and

gusset system 36 can also be molded integrally in the hull mold 10 in order to create a single unitary design.

The interior hull mold 22 forms the inside of the hull mold 10 and has a stringer, bulkhead and gusset system integrally built into the structure. This design allows the manufacturer to include the stringer, bulkhead and gusset system built into the structure as one composite piece. Traditionally, boats have their stringer, bulkhead and gusset systems added after the hull laminate is done. The benefits of including the stringer, bulkhead and gusset components into the hull include 1) a stronger design because the components are an integral part of the hull, not a later addition; 2) It takes less time to build the components into the boat during the closed molding process; 3) the inside of the hull will have a bright, beautiful finish, much like the outside of the part; 4) the engine compartment comes out of the mold already done thus eliminating the need for further finishing; and 5) the inside of the hull forward which makes up the interior space of the boat is finished reducing manufacturing cost.

The interior insert 20 is designed to take up the space that will eventually be the resin, or glue, and mat layer that makes up the inside of the hull laminate. Because each manufacture may use a different laminate depending on demand of physical properties of the part, the insert thickness will vary from mold to mold. The insert 20 allows the manufacture to produce a three dimensional core 18 utilizing the same mold 14 and 22 as the actual part uses. The core 18 must be thinner than the actual part because the manufacture adds resin and mat to the core. Without the inserts 16 and 20, the manufacture would have to produce a separate mold for the core, which would increase the cost of the molds and take up valuable floor space. This invention contemplates a manufacturer producing multiple molds for the part and the core separately if they decide to do so. However, the most economical way to produce the part is with the utilization of the inserts 16 and 20.

The stringer inserts 24, 26, and 28 and bulkhead inserts and core can be made of any material including, but not limited to, foam, fiberglass, plastic, or laminate and are designed to fill the stringers to allow the hull bottom 38 and hull sides 40 to be molded alone or separate from the stringers 24, 26, 28 and bulkheads 34. The stringers often use a different density of foam than the bottom of the boat. This allows the builder to make the stringers separate from the hull bottom and sides. The benefit is to have a balanced laminate. If the stringers, bulkheads and gussets were all part of the hull core, there would not be a complete laminate sandwich. The sandwich aids in laminate strength. It is preferred to have the same amount of mat

and resin on both sides of the core 18. If the stringers, bulkheads and gussets are attached to the hull core 18, there wouldn't be an opportunity to get mat underneath the stringers, bulkheads and gussets. This would potentially cause a weak point in the laminate that could jeopardize the strength of the product.

It is contemplated that the stringer inserts 24, 26, 28 could be eliminated and to mold the stringer, bulkhead and gusset systems into the hull core 18 directly. There may be products that don't demand such completely balanced laminates. In which case it would save time and money to include the stringer, bulkhead and gusset system into the core 18 and make them one piece.

The hull core 18 is what the laminate is built around. It is the first part in the lamination process to be built. The hull core 18 will start as an empty cavity in the shape of a boat hull. That cavity will be filled with core material to produce a three dimensional part which will ultimately be draped with mat and reinserted into the molds, less the inserts, and injected, poured, sprayed or rolled by hand. This will then produce the hull part. The foaming core agent will be vented out of the molds to allow for expansion and density control. The vents will be able to be open and closed utilizing a ball valve type vent. Once the core 18 is cured or hardened the vents can be opened and the hardened core can be cleared by use of a stop drill. This drill is slightly smaller diameter of the vent itself and will have a built-in stop to allow for depth control. This will also allow the builder to blow air into the mold to help release it from the mold.

The exterior insert 16 is designed to take up the space that will eventually be the resin and mat layer that makes up the outside 42 of the hull laminate. Because each manufacture may use a different laminate depending on demand of physical properties of the laminate, the insert thickness will vary from mold to mold. The exterior hull mold insert 16 will ultimately be the mat and resin layer for the bottom of the boat part.

There are two molds for each part. The interior hull mold 22 that makes the inside of the hull part. The exterior hull mold 14 makes up the outside of the hull part. The following is a brief description of how a mold is made. A CAD or computer- generated drawing is made, that drawing is downloaded then into a CNC machine. The CNC machine mechanically shapes a block (foam, wood, plastic, etc.) into the plug part. This plug is used to make a duplicate, in female form, of the part to be produced. The female form is the master mold. It will be appreciated that the mold 14 could be produced from a CNC type machine, eliminating the forming of the plug and going straight to the mold. Molds made of metals including aluminum, currently

utilized by the automotive industry, are made without the use of plugs or models. This invention contemplates the hand-making or lofting the hull plug although most manufacturers now utilize computers and robots.

With reference to figures 2a-2c, the steps for manufacturing a boat hull of the present invention are described.

The first step requires building all necessary molds 44 which in this instance includes exterior mold 14 and interior mold 22. The next step requires building inserts 46 that are to be later used inside the mold. These include exterior insert 16, interior insert 20, stringer inserts 24, 26, and 28, bulk head inserts, and transom inserts. Now that the molds and inserts have been created, the manufacturer can begin the specific process of making a hull.

The next step requires locating the inserts into the molds 48. The next step 50 requires blowing, inserting, injecting, or pouring core material into the hull bottom insides. Thereafter the venting step 52 allows excess coring material to come out of the mold to allow for expansion. The drilling step 54 takes place next where the vents are drilled with a stop drill in order to clear excess core material and to allow for a passageway for air to be blown into the core thereafter. The next step 56 requires blowing air into the vents in order to aid in the release of the core from the molds. Separating molds 58 is the next step which opens up the mold and exposes the core 18 to be later processed.

Once the molds are open, the hull core is sheeted 60 with material in order to separate the hull core from stringer and bulk head. It will be appreciated that this step is optional and is done only if the builder desires a separation of the hull core from the stringer and bulk head core. The next step requires removing the stringer and bulkhead inserts 62 from the molds. The next step is optional which includes removing engine compartment and transom inserts 64. This step 64 is only performed if the builder desires separation of the forward stringer and the bulk- head core from the engine compartment stringer and the transom core. The stringer and bulkhead inserts may be joined as one piece to the engine compartment stringers and transom inserts.

The next step 66 is also optional which includes sheeting or separating the engine compartment stringers from the engine compartment bulkheads. This optional step 66 is done only if the builder desires a different density core agent to be used in the engine compartment versus the forward stringers and bulkheads. Thus, the present design provides for a flexible construction that provides for a hull having different performance characteristics. The next step 68 requires joining the interior

and exterior molds after the sheeting and removal of insert steps have been completed.

With reference to Fig. 2b, the method of manufacturing a hull is continued. Once the molds have been closed, the next step 70 requires blowing, inserting, injecting, or pouring coring agent into all stringer, bulkhead and transom cavities. At this point, the builder may use a different density core material so as to meet the needs of the predetermined laminate construction. This step allows for flexibility of the hull design. The next step 72 allows for venting excess coring agent out of the mold to allow for expansion of the agent within the cavities. Once the coring agent has expanded and cured, the next step requires drilling vents 74 with a drill in order to clear excess core material so as to create an air passageway. Once the vents have been drilled out, the next step 76 requires blowing air into the vents in order to help release the core. The next step 78 requires separating the molds so as to provide access to the cavity. Once the molds are separated, the next step 80 requires removing all the cores from the molds, and then stripping the sheeting material from the hull core 82. After that has been completed, there is an optional step 84 wherein the manufacturer can cut the engine compartment stringer core from the transom core in the jig. This allows the builder to have a balanced laminate on transom if so desired.

The next step requires placing cores 86 into a proper position for mat draping. Thereafter, the step of draping the outside hull core 88 is performed where glue is used if so needed. Thereafter, hull mold insert 16 is removed 90 and then the interior insert 20 is removed at step 92. Thereafter draping the hull core 94 is performed.

With reference to Fig. 2c, the method of manufacturing a hull is further illustrated. The next step 96 requires shooting, spraying, rolling, or applying the exterior hull mold 14 with a protective material such as gel coat or polyurea. It will be appreciated that other protective material could be utilized. The next step 98 requires shooting, spraying, or rolling the interior hull mold 22 with a protective material as previously described. The next step 100 requires shooting, spraying, rolling, or injecting resin or glue in order to prepare the hull core 18. It will be appreciated that this may be done with the part in the molds and with the molds closed or open. The next step 102 requires closing and joining the molds together one last time. The next step 104 requires venting the excess resin or glue out of the mold so as to allow for expansion of the material therein. The next step 106 requires screwing or clamping the molds together to squeeze out excess resin or glue, the benefit of which is to assist in eliminating voids in the final laminate structure. The

part is then cured 108, wherein thereafter, vents are drilled 110 in order to clear excess resin or glue so as to create a passageway. The next step requires the blowing of air 112 into vents in order to help release the part. The final step 114 is actually releasing the part from the molds. It will be appreciated that the above- referenced steps can be varied in order to create the invention.

With reference to Fig. 3, the resulting boat hull 116 is depicted that has been made through using the steps outlined in Fig. 2 above. The components of the boat hull include an outer gel coat layer 118, an outer resin and mat layer 120, a central core 122, an inner resin mat layer 124, and an inner gel coat layer 126. A radius 128 is used with the gusset 36 and becomes integral with the structure. It will be appreciated that the gusset 36 can be located at predetermined locations throughout the boat hull 116 so as to provide structural integrity. A laminate layer 130 is positioned underneath the core 132 of the stringer 134. Each stringer 134 has an exterior gel coat 136, a mat with resin layer 138 and its own core 132. By placing the laminate layer 130 between the core 132 and the core 122, the core 132 can be made of different material as so desired by the manufacturer.

Further illustrated in Fig. 3 is the concave shape portion 140 disposed between stringers that can be located systematically throughout the hull. It will be appreciated that the concave shape could be continuous throughout the linear length of the hull. The concave shape is an integral part of the hull and is created during the close molding process. For illustrative purposes only, the concave shape 140 is only shown on the right side of the hull 116. The inner gel coat 126a, inner resin and mat layer 124a, and the core 122a, take on this concave shape which aids in the structural integrity of the hull. The outer gel coat layer 118 and the outer resin and mat layer 120 preferably employ a flat configuration as illustrated. However, it will be appreciated that they too could be configured to take on a concave shape by changing the shape of the mold.

An alternate embodiment to the present closed molded system includes modifying the stringers and bulkheads that form part of unitary hull. Typically, the ribs or stringers and bulkheads are glassed or glued into the hull bottom where the transition from the stringer or bulkhead to the hull bottom has no radius or very slight. The closed molding would allow for a predetermined radius to be added or built into the mold, which would increase the strength of the joint. It will also make cleaning easier and look more attractive.